Editing Maya numerals (section)

== Modified vigesimal system in the Maya calendar ==
[[File:La Mojarra Estela 1 (Escritura superior).jpg|thumb|266x266px|Detail showing in the right columns glyphs from [[La Mojarra Stela 1]].  The left column uses Maya numerals to show a [[Mesoamerican Long Count calendar|Long Count date]] of 8.5.16.9.7 or 156 CE.]] The "Long Count" portion of the [[Maya calendar]] uses a variation on the strictly vigesimal numerals to show a [[Mesoamerican Long Count calendar|Long Count date]]. In the second position, only the digits up to 17 are used, and the [[positional notation|place value]] of the third position is not 20×20 = 400, as would otherwise be expected, but 18×20 = 360 so that one dot over two zeros signifies 360.  Presumably, this is because 360 is roughly the number of days in a [[year]]. (The Maya had however a quite accurate estimation of 365.2422 days for the [[Solar Year|solar year]] at least since the early [[Maya civilization#Classic period|Classic era]].)<ref>{{cite book | title=The Mayans | publisher=Lucent Books, Inc. | author=Kallen, Stuart A. | year=1955 | location=San Diego, CA | pages=[https://archive.org/details/mayans00kall/page/56 56] | isbn=1-56006-757-8 | url-access=registration | url=https://archive.org/details/mayans00kall/page/56 }}</ref> Subsequent positions use all twenty digits and the place values continue as 18×20×20 = 7,200 and 18×20×20×20 = 144,000, etc.

Every known example of large numbers in the Maya system uses this 'modified vigesimal' system, with the third position representing multiples of 18×20. It is reasonable to assume, but not proven by any evidence, that the normal system in use was a pure base-20 system.<ref>Anderson, W. French. “Arithmetic in Maya Numerals.” American Antiquity, vol. 36, no. 1, 1971, pp. 54–63</ref>